The present invention relates to a device for shifting a railroad track such as by lifting and/or lining it. Generally speaking, devices for lifting and lining railroad track are associated with tamping machines which consolidate the ballast after the track has been shifted to its new surface and alignment condition. A large number of tamping machines, presently in use, carry track lifting and lining jacks cantilevered in front of the tamping machine, ahead of the tamping heads, and the loading on the axles of the tamping machines when they are performing a correcting lift or line operation, has on occasion been greater than desirable.
One attempt at reducing the loading on the front axle of tamping machines during a track correcting operation has been to provide the tamping machines with a jacking frame with jack shoes which engage the ballast externally of the track, on either side thereof. An example of this type of device is seen in the Stewart U.S. Pat. No. 3,299,833, issued Jan. 24, 1967. There are however, some instances in which it is not either desirable or possible to place ballast engaging jacks on the shoulders of the ballast on either side of the track, and under such conditions the front axle of the machine used have had to bear most of the reaction to the lifting and lining load.
An alternative proposal has been put forward in which the lifting and lining operation is performed on the tamping machine between the axles thereof so that the frame of the machine itself acts as a reaction point and distributes the loading more or less equally on the axles. This solution however, requires that the tamping machine be designed and built from the beginning to this style of design and it is not possible to adapt existing machines to use this solution.
A further suggestion which has been made in order to reduce some of the stresses on the tamping machine during an alignment operation, for a tamping machine in which the tamping heads, lifting jacks and lining jacks are cantilevered ahead of the front axle of the machine (which machine may, or may not, include shoulder engaging lifting jacks) has been to provide an elongated element which extends between the track rails and has thrust exerting means positioned between one of the track rails and the elongated element. In this configuration, one end of the elongated element is pivotally connected to the machine frame and the other end of the elongated element is pivoted and attachably connected to a truck on the track at a point spaced from the machine frame. One of the drawbacks of this solution was that whilst it helped to distribute some of the track aligning forces it did little or nothing to solve the problems caused by the track lifting forces. Furthermore, since the tamping machine itself still physically carried the track lifting and aligning apparatus, the track alignment forces were distributed in a somewhat inefficient manner.